Cost-Effective Seismic Isolation Systems for Structural Retrofit Applications

随着现有建筑物的老化和结构工程界对抗震性能和设计的进一步了解，越来越多的建筑物被发现是地震脆弱的。新西兰的设计规范和建筑方法与加拿大相似，基督城地震造成185人死亡，经济损失超过400亿美元。保护建筑物及其居住者的一种选择是隔震，它通常在建筑物的底部引入柔性层，限制传递到建筑物的力和建筑物内的变形。这提高了结构和非结构组件的性能，包括建筑元素，机械和电气系统以及建筑家具。然而，由于最初的建设溢价，隔震目前被视为一种奢侈的改造方法，其使用受到限制。** 传统的隔震方法要求在建筑物周围设置地震间隙，并在隔震平面的上下设置刚性层。此外，在改造的情况下，如果现有建筑被认为过于灵活，则必须在隔离之前首先对其进行加固。这些方面大大增加了实施隔离的初始成本。通过了解隔震系统与周围结构元件之间的相互作用，可以通过降低结构设计要求来最小化隔离新结构和现有结构的成本。除了降低初始成本外，这还将增加隔震改造可行的结构种类，使其适用于软层建筑物、设计不足的低层和中层建筑物，或需要增加楼层但原始结构无法适应增加的横向地震荷载的建筑物。** 通过限制结构损坏，通常更重要的是，减少对非结构部件的损坏，传统的抗震隔离已被证明可以减少新建筑的生命周期成本。改进的结构和非结构行为可以通过限制地震后的维修或拆除需求，进一步转化为最小化建筑物生命周期中的环境影响。然而，需要进一步的调查，改造应用和建筑物与降低成本的隔离配置。随着提高地震易发社区的安全性和可持续性的总体目标，拟议的研究将通过降低初始成本，同时探索潜在的生命周期效益，促进采用隔离改造项目。虽然拟议研究的重点将是建筑物改造项目，但研究将直接适用于新建筑物。研究结果将大大有助于在未来版本的加拿大国家建筑规范（NBCC），目前在地震设计常设委员会的计划地震隔离的规定。

As the existing building stock ages and the structural engineering community furthers its knowledge on seismic behaviour and design, an increasing number of buildings are found to be seismically vulnerable. In New Zealand, which has design codes and construction methods resembling those in Canada, the Christchurch earthquake resulted in 185 deaths and over $40 billion in economic losses. One option to protect buildings and their occupants is seismic isolation which introduces a flexible layer, usually at the base of the building, limiting both forces transmitted to and deformation within the building. This improves the performance of both the structure and the nonstructural components, including architectural elements, mechanical and electrical systems, and building furnishings. However, due to the initial construction premium, seismic isolation is currently viewed as a luxury retrofit method, and its use has been limited. **Traditional isolation approaches call for a seismic gap around the building and stiff layers both above and below the isolation plane. Furthermore, in the case of retrofits, if the existing building is deemed too flexible, it must first be stiffened before it is isolated. These aspects add significantly to the initial costs of implementing isolation. By understanding the interaction between the isolation system and the surrounding structural elements, the cost of isolating both new and existing structures may be minimized by reducing structural design requirements. Besides reducing initial costs, this would also increase the variety of structures for which isolation retrofit may be feasible, making it applicable to soft-story buildings, under-designed low-rise and mid-rise buildings, or buildings in which additional stories are desired but the original structure cannot accommodate the increased lateral seismic loads. **By limiting structural damage and, often more importantly, reducing damage to nonstructural components, traditional seismic isolation has been shown to reduce lifecycle costs for new construction. Improved structural and nonstructural behaviour can further translate into minimized environmental impacts over the lifecycle of the building by limiting needs for repair or demolition after earthquakes. However, further investigation is needed for retrofit applications and buildings with reduced cost isolation configurations. With the overarching goal of advancing the safety and sustainability of earthquake prone communities, the proposed research will promote the adoption of isolation for retrofit projects through decreasing initial costs while also exploring potential lifecycle benefits. While the focus of the proposed research will be on building retrofit projects, the research will have direct applicability to new buildings. The findings of the research will contribute significantly to seismic isolation provisions in future versions of the National Building Code of Canada (NBCC) which is currently within the plans of the Standing Committee on Earthquake Design.